Surface plasmon resonance (hereinafter referred to as SPR) sensor is a measuring device which monitors the interaction of biomolecular on a surface of the sensor chip on the molecular level. One molecule is immobilized on the surface of the sensor chip, and sample solution including another molecule which interacts with the immobilized molecule is provided on the surface of the sensor chip though a microchannel. SPR signal reflecting a slight amount of refraction index gradient near the sensor chip surface resulting from the association or dissociation of the aforementioned interacting molecules is detected.
The gradient with time of the signals are monitored in real-time and displayed as a time course in a graph so called a sensorgram. Thus, as monitoring the interaction of such molecules on the surface of the sensor chip in real-time as the interaction occurs, the target (e.g. micro-substance) specifically associate relative to the surface of the sensor chip.
Different methods of such measuring device using SPR depending on the optical alignment have been disclosed. One measuring device is described in Real-Time Analysis of Biomolecular Interactions, K. Nagata, H. Handa, P22, Ed. Springer-Verlag Tokyo. In addition, another measuring device using a small SPR sensor disclosed in JP1019768A and JP11344437A.
FIG. 6 illustrates a diagram indicating a structure of the sensor disclosed in JP1019768A. A sensor 100 includes a substrate 101 and a light source 102 provided thereon. A light 110 emitted from the light source into a housing 103 is polarized at a polarizer 104. Further, the light 110 is reflected at a SPR film 105 and reflected at a flat mirror 106. Finally, the light 110 reaches a detector array 107.
FIG. 7 illustrates a diagram indicating a structure of the sensor disclosed in JP11344437A. A sensor 200 includes a surface emitting laser 202, a one-dimentional CCD sensor array 203 and a Si substrate 201. The surface emitting laser 202 and the one-dimensional CCD sensor array 203 are arranged on the Si substrate 201 along a line extending in horizontal direction in FIG. 7. To maintain its mechanical strength, the Si substrate 201 is supported by an insulating substrate 204. Terminals 205 are drawn from the insulating substrate 204 to drive the surface emitting laser 202 and take out signals from the CCD sensor array 203. A cylindrical lens 206 is provided above the surface emitting laser 201 to expand the laser light in the arrangement direction of the CCD sensor array 203. These elements are molded with a light-transmitting polymethylmethacrylate resin 207 to construct a sensor apparatus. The expanded laser light is totally reflected by an outer surface of a metal thin film 208, and the focal length of the cylindrical lenses 206 is set such that the intensity of the totally-reflected light can be measured by the CCD sensor array 203 corresponding to its incident angle.
If the light is emitted from the light source provided separately from the sensor, a optical axis may be misaligned due to vibration so as to disenable the measurement. The aforementioned sensors 100 and 200 integrally include the sensor elements such as the metal thin film, the light source and the detector so as to improve the shockproof, however; the sensors 100 and 200 are not configured for seeking the portability. Specifically, the sensors 100 and 200 have complicated structures and less durability in a shaken condition. Further, the sensors 100 and 200 include such complicated structures and the detector array 107 and 203, so that microminiaturization of the sensor has been difficult.
Thus, a need exists for the SPR sensor to have high shockproof and durability, or to microminiaturize the SPR sensor.